Coded track circuit signaling system



Oct. 5, 1943.

' .T. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM ETO Filed Oct. 11, 1941 Patented Oct. 5, 1943 SYSTEM Thomas J.- Judge, Rochester, N. Y., assignor to gnal Company, Rochester,

General Railway Si N. Y.

Application October 11, 1941, Serial Nor 414,585

I .1 Claim.

The present invention relates ,,to railway, signaling for a comparatively short single track section connecting two double track;.sections, and more particularly tosignaling ior; moving traific in both directions over-such single track section without the employment of line Wires.

In view of the large expense involved in buildins a bridge or in building a tunnel it is quite common to build such bridge or tunnel wide enough to accommodate a single track instead of two tracks even though such bridge or tunnel is to be built for adoubletrack railroad. A Obviously, special signaling must -beprovided to prevent the movement; of trains overlthis single track section in both directions at the same time In accordance with the, present invention it is proposed to provide a signal governing the entrance of tramc into each end of the single track section extending through a tunnel or over a bridge, to provide approach sections to the rear of each of these signals, to provide a dual track circuit having a track relay at each end thereof for this single track sectionand to render .only one of these track circuits effective if a particular approach section is occupied by an approaching train. More specifically, i t is proposed to normally connect a source of energy to each end of thesingle track section and to substitute a track relay for this source of energyata particularend ofthe single track section when the adjacent approach section becomes occupied by a train, so that this track relaymay control the associated signal in accordance with conditions of trafiic in' the single track sectionv and the approach section located beyondsuch single track section in advance of the signal. Other objects, purposes and characteristic 'features of the present invention will be pointed out in the specification hereinaftenwhenconsidered in the light of the accompanying drawingfin which drawing: 1

Fig. 1 shows a single track section of railway connecting two double .tracksections signaled' in accordance with the present invention; and Fig. 2 illustrates how the several kinds of sources of current are, derived from a single,

source. of alternating current.

Structure Referring to Fig. l lo-f the drawing the illustration represented by the. referencecharacter TU constitutes a tunnelth'rou'gh a mountain or a bridge extending over astream, which bridge ortunnel is only widefenough to accommodate a single track section of railroad and has been designated TS. The left-hand endof this singleftrack' section TS is provided with a signal S] for governingeast-bound traflic into the section and the east end of this singletracksection is provided with a signal S2 for governingwestbound traflic-into the single track section. These signals may be of any suitable construction and may constitute either a semaphore signal, a multiple aspect'color light signal, or a movable spectacle search-light signal, and for convenience only a multiple aspect color light signal has been illustrated. As shown these signals are provided with a proceed lamp Y and a stop lamp R it being understood that a train moving over a bridge or through a tunnel should proceed at limited speed as is permitted by the caution signal unit Y. To the rear of the signal SI has been provided an approach section AT and to therear of the signal S2 has been provided an approach section BT. Theseapproach sections AT and BT are provided with track relays ATR and BTR, respectively, and are located at the end of the approach section adjacent the signals SI' and S2, respectively. These approach track relays ATR and BTR are connected to full-wave rectifiers AR and BR, respectively, energized from track transformers IRA and TRB, respectively. The opposite ends of these approach sections AT and BT are provided with the usual track transformer TRAS and TRBS, respectively, which transform: ers are energized from an alternating current transmission line, the secondary windings of these transformers are provided'with the usual series resistance 10 and II, respectively. jIt'is readily understood that under normal conditions with the approach sections AT and BT unoccupied the track relays ATR and BTR Will be energized. Although as illustrated the approach track sections AT and BT are normally continuously energized causing their track relays to con+ tinuously p assumeftheir energized position, 'it should'be understood that these approach track sections may be energized by coded current in which event code following track relays controlling de-coding apparatus will be employed, such, for instance, as is employed in the single track section TS which will be presentlydescribed'.

Across the rails of the leit-handend of the single track section TS is connected one winding of a track transformer TRI, whereasasimilar winding of a track transformer TRZ is connected across the track rails at the east end ,of' this single track section TS.', These transformers TRI and TRZ at times apply energy to thetrackf section and at other times receive energy from scribed, like reference characters having dis-,

tinctive exponents, prefixes or sufiixes being er'nployed to signify like devices at the east end *of this single track section TS.

The track transformer TRI :connected' a" source of alternating current BX-NX (see Fig; 2) through front contacts I4 and I5 ofthe ap I proach track relay ATR, through the series resistance I5 the front contact ll of the relay IFRP and through the contact. I8 of the coder ICT. This coder ICT may be of any suitable construction such as a motor operated rotary contact or an oscillator device havinga contact 22 which is intermittently closed by oscillation, the construction being such that this contact is closed, say 120 times per minute. I Both of these types of 'codersare .well known in" the art and therefore the coders ICT and 2CT are illustrated conventionally. The codingfdevicefICTis electrically controlled andasshownis normally energ'ized through a front contact I9 "of the approach track relay ATR. Th'e relay 'IF'RP is a normally energized relay which is energized through a circuit closed when the decoding apparatus, presently to be described, manifests danger trafiic conditions, that is, this relay is energized through a circuit including back contacts and II of the front and back repeater relays IFP and IFBP, respectively.

Whenthe approach track relay ATR is deenr'gized, as would be the case when the approach track section AT is occupied, the free; winding of the transformerTRl isdisconn'eoted from the coding" apparatus and is connected to suitable decoding apparatus through the medium of back contacts I4 and I5 of the approach track relay ATR. This decoding apparatus consists of a code following track relay IT energi'zed' througna series resistance 24 and a fullwave rectifier IR and includes front and backrepeater re'layslFPjand IFBP. This code following track relay- IT' is provided with a code following contact 25 which when in its energized position closesfan ei'ierglzing circuit :for the n w dropping front repeater. relay IFP and which when in its retracted position closes an energizing circuit through the, front contact 26 of the-relay IFP and through the winding of the slow dropping back repeater relay IFBP. These slow dropping relays IFB and 'IFBP. are each madeslow dropping in any suitable manbe illuminated upon closure of the approach contact 21 and will assume the proceed caution condition, in which the lamp Y is energized, if

I east end of the section have been designated by like reference characters having distinctive exand sufiixes.

' Operation From the foregoing it is apparent that under ponents, prefixes normal cleartrafiic conditions both of the approach track relays ATR and BTR are energized and by the closureof theirrespective front contacts I I -"-I5 and F -I5? will apply coded current 'to'both ends-ofthe s'ing'l'e' track section TS and will disconnect both of the code following track reiaysir and IT from the track'c'ircuit-so thatthe de-co'ding apparatus will be 'deener'gized and will cause their associated signals to indicate danger trafliccondition's if -the' approach contacts \21 (and 21 were to be closedwhich'they cannot be. That is,-these approach contacts 21 and 2I are open because-they are back cont'actsof the normally energized approach track relays-ATE and BTR, r'espectively.

, Let us now assume that an east-bound train 'approaches' on one of thetwo tracks connected through the medium of the track switch Swl to the-left-h'and end of the approach section-AT. soon as this train passes over the points of the track switch Swl and onto the approach track section AT the wheels and axles of this train cause deenergization of the approach track rela-y' ATR for obvious reasons. Dropping of the track relayATR will disconnect the coded alternating current source created by the coder ICT and will instead connect the decoding apparatus her as, for instance, by the provision of slugs of conducting material of low resistance surrounding their cores, as indicated by the shaded area, 'and bybeing short circuited by reversely poled half-wave rectifiers as illustrated. These repeater relays IFP and IFBP are energized from a source of direct current having terminals BL and CL, which source, as shown in Fig. 2 of the drawing, is derivedfrom a full-wave rectifier R energized from an alternating currentsource.

'As illustrated the signal SI is normally a dark signal because theapproach' contactll com prising a back contact of the approach track relay ATR is normally open, but this signal will comprisingthe code following track relay IT, its back and front repeaterrelays IFP and IFBP, and associated, apparatus. Assuming that the single track section TS, and the approach section next in advance thereof with respect to the signal SI, is unoccupied, under this condition the code'following-track relay IT will pick up and drop away times per minute in response to the coded current applied to the east end of this singletrack section TS, resulting in the continuous'energization of theback and front repeater relays .IFP and 133?, respectively. .With these relaysf'lFPand IFBB, or either of them, in their energizedcondition the check relay IFRP is deener'gizjedandupon dro'ppinggaway opens the check "contact 'I'I This'ch'eck relay IFRP assures against the application o f a code at the west "end of the track se'ction TS in the event either (if the relays l near IFBP should fail to drop "upon discontinuation ."Of the received code.

With 'the front and back' repeater relay IFBP continuously 'ener'gize'dand with the approach track relay ATR-deenergizedydue to its occupancy by the east-bound train, an energizing ciron the approach section AT may therefore proceed into the single track section TS under conditions authorized by the illumination of the yellow lamp Y of the signal SI.

The entrance of the east-bound train upon the single track section TS will, of course, cause continuous deenergization of the code following track relay IT and will cause the signal SI to assume its stop condition in which condition its red aspect R is illuminated. When the rear end of the train leaves the approach section AT the approach contact 21 opens and the signal SI is extinguished. As the east-bound train proceeds through the single track section TS and enters upon the approach section BT no change in traffic condition as manifested by the signal SI takes place, and if approach contact 21 were closed the signal SI would still indicate stop. Also, when the east-bound train under consideration has passed entirely out of the track section TS and occupies the approach section BT, no change in the signal aspect of the signal SI takes place, that is, this signal SI would continue to give a danger signal indication by the illumination of its red lamp R if the approach contact 21 were closed, because the presence of the east-bound train on the approach section BT causes deenergization of the approach track relay BTR which results in disconnecting the coding circuit including the coding contact I8 of the coder ZCT from the east end of the single track section TS, so that no coded current can reach the decoding apparatus at the west end of the single track section TS. There is another reason why the signal SI will not indicate proceed even if the approach contact 21 were closed and that is because the approach track relay ATR which is now assumed to be in its energized condition disconnects the decoding apparatus including the code following track relay IT and its front and back repeater relays IFP and IFBP from the west end of the track rails of the single track section so that front contact 28 of relay IFBP remains open. Attention is directed to the fact that signal S2 clears as soon as the eastbound train has entirely passed it. This is based on the assumption that the single track section TS and the approach section AT in advance thereof are unoccupied. This clearing of the signal S2 is in part due to the fact that approach section ET is occupied to cause closure of approach contact 21 As soon as the east-bound train passes off of the approach section BT and over the track switch SwZ into one of the tracks of the double track section connected by switch SwZ to approach section BT, all of the apparatus returns to its normal condition heretofore described. The apparatus is symmetrical and functions identically the same for a west-bound train movement over the track illustrated as for an east-bound train movement.

The applicant has thus provided signaling apparatus for a single track section in which coded current is normally applied to both ends of a single track section and in which decoding apparatus is substituted for the code applying apparatus at a particular end of such single track section when a train is about to enter that end of the single track section, the presence of the train being manifested through the medium of an approach section; Although code is applied to both ends of the single track section at the same time and although the application of these codes to opposite ends of the same single track section may cause what is commonly known as a code fight, this code fight is of no material importance because there are no code following track relays or decoding apparatuses connected to the ends of a single track section under the condition assumed. As soon as one of the decoding track relays is connected to the single track section no code fight can exist because simultaneous with such connection of th code following track relay and associated apparatus the code applying apparatus at that end of said section is disconnected. It is, of course, understood that the particular system which has been illustrated has been selected for the purpose of describing the present invention with the view of disclosing the underlying principles of the invention by apparatus embodying the invention and the functions accomplished by such apparatus and that this particular embodiment of the invention has not been illustrated to show all forms that the invention may take and that various changes, modifications, and additions may be made to adapt the invention to the particular problem encountered in practicing the invention all without departing from the spirit or scope of the invention, except as demanded by the scope of the following claim.

What I claim as new is:

In combination, a stretch of track, an approach section adjacent each end of said stretch over which approaching trains moving in opposite directions may enter said stretch, two intermittently closed coding contacts one at each end of said stretch, a source of current at each end of said stretch included inseries with the associated coding contact, a code following track relay for each end of said stretch, decoding means controlled by each of said code following track relays and rendered active when the associated code following track relay follows the impulses of a code, a signal at each end of said stretch for,

governing the movement of traflic into said stretch from that end and controlled by the associated decoding means, a track circuit for each approach section including an approach track relay at the end adjacent said stretch, contacts controlled by each of the approach track relays of the approach sections for connecting the source of current and the coding contact included in series therewith to that end of the track rails of said stretch when the adjacent approach track relay assumes its energized position and disconnecting said source of current and the coding contact included in series therewith and connect-.

ing the code following track relay at that end of said stretch to the track rails at that end of said stretch when the adjacent approach track relay assumes its deenergized position, and checking means for preventing the application of a code to a particular end of said stretch of track when the decoding means at that end of said stretch assumes its active condition.

THOMAS J. JUDGE. 

